"Porphyritic" Quotes from Famous Books
 ... it. It sometimes gives place to quartz and reddish clay schists, much baked by heat. This is the usual geological condition on the right bank of the Cataracts. On the other side we pass over masses of porphyritic trap, in contact with the same mica schists, and these probably give to the soil the great fertility we observed. The great body of the mountains is syenite. So much mica is washed into the river, that on looking attentively on the stream one sees myriads of particles floating ...
— A Popular Account of Dr. Livingstone's Expedition to the Zambesi and Its Tributaries • David Livingstone
... with all his power." Humboldt examined some of the remains of this road, and described as follows a portion of it seen in a pass of the Andes, between Mansi and Loxa: "Our eyes rested continually on superb remains of a paved road of the Incas. The roadway, paved with well-cut, dark porphyritic stone, was twenty feet wide, and rested on deep foundations. This road was marvelous. None of the Roman roads I have seen in Italy, in the South of France, or in Spain, appeared to me more imposing than this work of the ancient ...
— Ancient America, in Notes on American Archaeology • John D. Baldwin
... or zoisite, quartz and garnet may often be identified. Biotite and primary hornblende suffer comparatively little change; olivine disappears, and garnet, talc and tremolite or anthophyllite take its place. The original structures of this group of rocks (ophitic, porphyritic, poikilitic, vesicular, &c.) gradually fade away, and merge into those of the metamorphic amphibolites. Even when the greater part of the rock mass has suffered complete reconstruction, kernels or phacoids may remain, showing the old igneous structures, though ...
— Project Gutenberg Encyclopedia
... I have read a purely geological paper which has interested me so greatly. I was all the more interested, as in the Cordillera I often speculated on the sources of the deluges of submarine porphyritic lavas, of which they are built; and, as I have stated, I saw to a certain extent the causes of the obliteration of the points of eruption. I was also not a little pleased to see my volcanic book quoted, for I thought it was completely dead and forgotten. What fine work will Mr. Judd assuredly ...
— The Life and Letters of Charles Darwin, Volume II • Francis Darwin
... calceolaria, eupatoria, and red and purple gentians; around and on the Arenal, a uniform mantle of monocotyledonous plants, with scattered tufts of valeriana, viola, and geranium, all with rigid leaves in the characteristic rosettes of super-alpine vegetation; and on the porphyritic and trachytic sides of Chimborazo, lichens alone. Snow then covers the last effort of vegetable life.[15] The change in the architecture of the houses indicated, likewise, a change of altitude. The open bamboo huts, shingled with banana leaves, were followed by warmer adobe ...
— The Andes and the Amazon - Across the Continent of South America • James Orton |
